There are a few things you can do to reduce the bulk in the back.I start by reducing the amount of tape used,if it's good tape it should be alright to use smaller pieces.Also most people cut the paper in 1 inch strips and fold over 1/4 inch, I cut them in 3/4 inch strips and fold over 1/4 inch,this saves paper and there is not so much of it in the back.The thinner the paper the better,I usually use Slab paper or Orgami paper,Orgami paper is perfect since it is so thin.You could also use wrapping paper.It will still be a little lumpy but,it should cut down on some of the bulk in the back.I hope this helps.Thanks for your wonderful comments.
Lastel :)